Jaw movement simulation

ABSTRACT

An upper frame including parallel side arms is supported on the patient&#39;s ears and attached to a transverse rod supported on the bridge of the patient&#39;s nose. A record plate depends from each side arm overlying each of the patient&#39;s temporomandibular joints. A lower frame is attached to the lower jaw by means of an adjustable clutch. Adjustable side arms carrying movable styluses engage the record plates on the upper frame. Movement of the styluses over the record plates is monitored to obtain measurements of the joint movements. A tooth separator swingably mounted on the transverse rod of the lower frame separates the rear teeth slightly when the jaw movements are being measured. After the hinge axis position has been located on the record plates, an adjustable straight edge is utilized to indicate the true horizontal plane of reference formed by the two hinge axis points and the point on the patient&#39;s nose. The stylus movements can be monitored mechanically or electronically and the resulting measurements utilized to set an adjustable dental articulator or to select preformed motion analogue blocks having pathways for guiding the styluses of an articulator.

This invention relates to jaw movement simulation and more particularlyto improvements in apparatus for recording or analyzing jaw movementsand the methods of utilizing such apparatus to measure jaw movements.The invention further relates to a system for obtaining simulated jawjoint action for use in a dental articulator by utilizing the jawmovement measurements obtained through the use of the apparatus.

In the making of dental prostheses and the analyzing and treatment ofother jaw disorders, it is desirable to have means for simulating theindividual patient's jaw movements. Consequently, a variety of dentalarticulators have been developed for such purposes. While these areuseful instruments with varying degrees of accuracy of simulation, theyall only provide fairly rough approximations of the patient's actualtemporomandibular joints. The shortcomings of these devices in thisregard are discussed extensively in U.S. Pat. No. 3,452,439, issued toRobert L. Lee, the same inventor as the present invention. In thispatent there is disclosed a system for much more accurately simulatingif not actually duplicating a patient's jaw movements. Briefly, thesystem disclosed therein records jaw movements in solid plastic recordblocks. The information stored in these blocks is then transferred bytransfer apparatus to prepare a second set of plastic blocks in whichare formed guide pathway openings which closely simulate or duplicatethe patient's jaw joint movements. These "analogue" blocks are thenmounted in a dental articulator to simulate the patient's jaw movements.The walls of the openings in these analogue blocks are three-dimensionaland control movement in the 6° of freedom.

While the system disclosed in the aforementioned Lee patent is highlyaccurate and therefore a very significant contribution to this field, itis relatively costly to obtain a set of analogue blocks through thissystem. There are many steps to follow in the procedure which takeconsiderable time and skill such that normally the work must be done bya dentist, who requires considerable training to become adept at theprocedure. In effect, it is a very precise and personalized procedure toobtain a set of custom-made guide blocks for reproducing jaw movements.Consequently, the system has not been widely used being largely limitedto research and larger dental schools in that the cost and complexity ismore than the usual dentist can justify, and more costly than thepatient is willing or capable of paying. Therefore, a need exists forsimplifying and reducing the cost of obtaining jaw movements while stillmaintaining acceptable accuracy.

The present invention accomplishes this by introducing severalimprovements in apparatus and the method of utilizing this apparatus andother available equipment. As one step in the procedure, it is necessarythat certain information regarding the patient's jaw movements beobtained and such information should be obtained relatively quickly andeasily and yet accurately. Thus there is provided improved apparatusincluding a maxillary frame having a pair of side arms with a rigidrecording plate perpendicularly mounted on each of the arms to bepositioned over the hinge axis of the patient's temporomandibularjoints. Also provided is a lower frame which is fixed to the patient'smandible and which has a stylus or transducer probe mounted to engageeach of the two recording plates on the maxillary frame to monitor orrecord mandibular movements.

By utilizing a pair of writing elements as styluses for engaging a papergrid on the recording plates, a curve or line may be traced directly onthe grids when the patient's mandible moves from centric relationposition to a protrusive position. From this recorded curve variousinformation may be obtained relating to the configuration of themovement of the jaw joints. For example, one important parameter whichcan be measured is the slope of descent with respect to a horizontalplane of reference. This horizontal reference plane is formed from apoint on the nose and the hinge axis line in centric relation position.By means of a special adjustable straigt edge tool mounted on the upperframe, the horizontal reference plane may be scribed on the two verticalrecord plates. The angles can be measured with a suitable tool such as aprotractor.

If greater accuracy is desired, the writing element may be replaced by asuitable transducer probe which will monitor the movement electronicallywherein the information can be recorded in a variety of fashions or canbe shown on a suitable display or other readout device. For example, acurrent inducing probe may be moved over a grid of electrical wiresembedded in the record plate to obtain a readout of the protrusivemovement of the probe over the wires. The probe referred to above may bespring mounted in a holder so that movement of the probe in the holderis measured through photoelectric means to obtain a readout of the sideshift when the mandible is in a side border movement.

Another parameter of condyle movements relative to the upper jaw is theside shift. This includes both the so-called immediate side shift,progressive side shift and total side shift. Such information isobtained by a displacement technique involving the lower frameapparatus. The styluses on the lower frame which engage the grids on theupper frame are movably mounted on the side arms of the lower frame.Thus these styluses may be slid into engagement with the grids when thepatient's mandible is in centric position and the styluses locked insuch position. A suitable marker is mounted on the outer end of thestylus with its inner or medical side in engagement with the structuresupporting the stylus, or other suitable reference surface. The stylusesare then unlocked and the patient's mandible is moved to one side (as inchewing) to the extent possible to demonstrate any immediate side shiftof the condyles. This motion will cause the stylus mountings on the sideopposite to the direction the jaw moves to slide inwardly on its stylusbecause the stylus inner end is in engagement with the stationary gridon the upper frame apparatus. The marker on the stylus becomescorrespondingly spaced from the reference surface. Thus it is a simplematter to measure the distance between the reference surface and themarker, which represents the displacement of the stylus and the condylarside shift. The characteristics of the side shift timing can also beobserved as to .[.wehter.]. .Iadd.whether .Iaddend.the side shift isimmediate, progressive, nonprogressive, or both immediate andprogressive, or does not exist at all.

Again, these measurements may be performed entirely mechanically andmanually or they may be monitored and measured electronically.

While measuring these jaw movements, it is important that the patient'steeth not restrict the full range of movement so that thecharacteristics of the joints may be determined as accurately aspossible. Further it is particularly important that the patient'smandible be easily and repeatedly movable into centric relationposition. Hence the patient's rear teeth should be slightly separatedduring such movement. The prior art discloses a rather cumbersomeprocedure for obtaining such separation which involves fabricatingclutches for both the mandible and maxilla. The present inventionemploys a simplified tooth separator which is mounted on the lower framein a manner such that the patient's upper front teeth or ridges cansimply rest on the separator. Also the separator is conveniently mountedto be quickly moved out of the patient's mouth so that the operator caneasily place or remove the clutch from the teeth. The separator isadjustable in several respects to accommodate various jaw sizes andrelationships.

More specifically, the tooth separator is pivotally mounted on atransverse rod on the lower frame which is the same rod supporting theside arms of the frame. The frame is attached to the patient's lower jawby means of an adjustable clutch mounted on a strut which in turn isconnected to the transverse rod. An adjustable screw extends through thestrut and engages a lower surface on the tooth separator to providevertical adjustment for the separator.

The information obtained by utilizing the above described apparatus andmethods can be employed for adjusting various dental articulators andthus the apparatus and methods are useful just for that reason alone.The information may also be used with the more accurate preformedanalogue guide blocks described above in connection with theaforementioned Lee patent. With the system of the Lee patent analogueblocks simulating the joint motions of patients have been accumulatedfor a large number of patients representing a considerable cross sectionof jaw joint anatomy and physiology. The information obtained from thislarge group of actual patients has been analyzed and it has beendiscovered that while all such analogue blocks are different,nevertheless the joint movements of patients have certain similarcharacteristics. By classifying these characteristics on the basis ofparameters of jaw movement which can be measured by the apparatusdescribed above, it has been found that they fall into a statisticalnormal curve distribution. Therefore, most of these patients can belogically classified into a relatively small number of groups so thatanalogue blocks made in accordance with the average values of thepatients in a particular group of these readily measurable parameterswill provide a reasonable approximation of the patient's condylemovements. These approximations are much more accurate than that whichcan be obtained through the use of the typical .Iadd.dental.Iaddend.articulator. Since a patient can be so catagorized orclassified, a group of .[.standarized.]. .Iadd.standardized .Iaddend.oraverage value blocks may be made by inexpensive plastic moldingtechniques and a supply or inventory of such standard sizes can be madeavailable at a relatively modest cost. Thus the individual dentist maymake the various necessary jaw measurements utilizing the apparatus andmethods described above, and then simply select the set of preformedanalogue guide blocks which most closely approximate his patient's jawmotions. These blocks are then mounted in a standard dental articulatorand used to simulate that patient's jaw movements. By the use of thesystem the average dental practitioner can provide more precise orindividualized treatment at a reasonable cost.

Further features and advantages of the invention will be apparent byreference to the following detailed description and drawings in which:

FIG. 1 is a perspective view illustrating the apparatus of the inventionmounted on a patient;

FIG. 2 is a perspective view of the upper frame apparatus;

FIG. 3 is a cross-sectional view taken along the lines 3--3 of FIG. 2 toillustrate the mounting of the transverse rod of the upper frame withrespect to the side arms;

FIG. 4 is a cross-sectional view on lines 4--4 of FIG. 2 illustratingthe mounting of the nose pointer;

FIG. 5 is a front elevational view of the nose pointer;

FIG. 6 is a perspective view of the lower frame apparatus;

FIG. 7 is a side elevational view of the lower frame apparatus;

FIG. 8 is a plan view of one of the styluses of the lower frame inengagement with the record plate of the upper frame with the sidemovement marker in its initial position;

FIG. 8a is a view like FIG. 8 with the stylus being urged against therecord plate by an elastic band;

FIG. 9 is a view like FIG. 8 after the lower frame except the stylusholder has been shifted sideways on the stylus away from its marker inresponse to immediate side movement of the patient's mandible;

FIG. 9a is a fragmentary view of FIG. 9 showing the displacement forfull side shift;

FIG. 10 is an enlarged perspective view of the tooth separator of thelower frame with the separator in the position .[.is.]. .Iadd.it.Iaddend.occupies outside of the patient's mouth;

FIG. 11 illustrates the tooth separator in its operating position;

FIG. 12 is a cross-sectional view of the separator on lines 12--12 ofFIG. 11 illustrating the vertical adjustment of the separator;

FIG. 13 is a side cross-sectional view on lines 13--13 of FIG. 12further illustrating the configuration of the separator;

FIG. 14 is a top perspective view of a tool for locating the exacthorizontal plane of reference formed by the jaw hinge axis and a pointon the patient's nose;

FIG. 15 is a side elevational view of the tool of FIG. 14;

FIG. 15a is a cross-sectional view of the dimple of FIG. 15;

FIG. 16 is a side elevational view of a patient with the tooth separatorin use;

FIG. 17 is a side elevational view of the recording frames in use on thepatient's head and with the protrusive movement of the mandible shown inphantom lines;

FIG. 18 is a lower perspective view of the horizontal reference planetool positioned on the upper frame;

FIG. 19 is a side elevational view of the horizontal reference planetool on the upper frame;

FIG. 20 is an enlarged view of a record plate with the plane ofreference and the movement curves marked thereon, and a protractor formeasuring the curve angle from this plane;

FIG. 21 is a schematic perspective view of apparatus for electronicallymonitoring jaw movements;

FIG. 22 is a perspective view of a jaw movement simulator;

FIG. 23 is a rear elevational view of the instrument of FIG. 22;

FIG. 24 is a cross-sectional view on the line 24--24 of FIG. 23illustrating the adjustable mounting for one of the guide boxes;

FIG. 25 is a cross-sectional view on the line 25--25 of FIG. 23illustrating the adjustable mounting of the medial wall of the guidebox;

FIG. 26 is a cross-sectional view on line 26--26 of FIG. 25 illustratingthe shape of the guide box;

FIG. 27 is a top view of the guide box showing the adjustability of themedial wall;

FIG. 28 is a perspective view of a set of analogue blocks havingopenings for guiding an .[.aritculator.]. .Iadd.articulator.Iaddend.lower frame to simulate a mandibular movement; and

FIG. 29 is a chart illustrating use of preformed standardized analogueblocks.

UPPER HEAD FRAME

Referring first to FIG. 1 there is shown an upper frame 12 and a lowerframe 14 mounted on a patient's head 10. As can be seen the upper frameis mounted on the patient's nose and ears, while the lower frame isattached to the patient's lower jaw. Referring to FIG. 2, it may be seenthat the upper frame apparatus includes a pair of side arms 15 formed ofrigid materials such as metal or plastic and having a squarecross-section. The side arms 15 are slidably mounted in support blocks18. A transverse rod 20 is also slidably mounted in the support block 18in perpendicular relation to the side arms 15. As can be seen from FIG.3, the transverse rod 20 also has a square cross-section so that it ispermanently held in perpendicular relation to the side arms even thoughthe side arms may be moved forwardly and rearwardly to be suitablyadjusted on the patient's ears and may be moved sideways to fit thewidth of the patient's head. Suitable clamping screws 22 and 23 extendthrough the block 18 to lock the side arms in a selected position. Morespecifically, the outer screw 22 clamps the upper and middle segment 18aand 18a (FIG. 3) of the clamp 18 to fix the side arms laterally withrespect to the transverse rod 20 while the inner screw 23 clamps theupper and lower segments 18a and 18c to fix the rearward or forwardmovement of the side arms with respect to the transverse rod.

A stiff or rigid reference or recording plate 24 is attached to each ofthe side arms 15 adjacent the rear end of the arms by a pair of screws25 or other suitable means. The plates are mounted in fixedperpendicular relation with respect to the arms 15 and 16 and extenddownwardly to be positioned in front of the patient's ears as seen inFIG. 1. Each plate has a curved lower portion which extends rearwardlytowards the ear so that the plate completely covers the area of thepatient's temporomandibular joint when mounted on the patient's face asseen in FIG. 1. On the .[.other.]. .Iadd.outer .Iaddend.surface of eachplate is a grid of intersecting lines which are perpendicular to eachother, and therefore the vertical lines are perpendicular to the sidearms 15 and 16 and the horizontal lines are parallel to the side arms.The grid may conveniently be formed on a separate sheet of paper held byadhesive to the plate in a manner such that the sheet is readily.[.removed.]. .Iadd.removable .Iaddend. from the plate. A flexible strap26 attached to the rear end of the side arms helps maintain the upperframe on the patient's head.

Mounted on the center of the transverse rod 20 is a nasion support 28which rests on the bridge or nasion of the patient's nose. As can beseen from FIG. 5, the support 28 has a smoothly curved central sectiontapering to larger .[.diamger.]. .Iadd.diameter .Iaddend.flanges on theends. The curvature of the support is not symmetrical and it may berotated on the support 20 to best conform to the patient's nasion.

Also mounted on the transverse rod 20 is a pointer assembly 30comprising a mounting block 31 which is slidably mounted on thetransverse rod 20. The mounting block 31 may be locked in a desiredposition by means of the screw 32 attached. A pointer 33 is mounted onthe lower end of the block 31 extending generally parallel to the rod 20towards the support 28. With this arrangement, it may be seen that thepointer is transversely adjustable on the rod 20 but remains fixed.Iadd.in .Iaddend.a preselected distance below the transverse rod 20 andparallel to the rod.

LOWER HEAD FRAME

Referring to FIG. 6, it may be seen that the lower head frame 14includes a transverse rod 36 on which is mounted a pair of side arms 38.The side arms are each attached to the transverse rod 36 by a supportingunit 40 which keeps the side arms perpendicular to the transverse rod 36while permitting them to be individually slid transversely on the rodand locked by means of a screw 41; individually moved rearwardly andforwardly by means of the adjusting screw 42; and moved angularly withrespect to the transverse rod 36 by means of the adjusting screw 43 allas seen in FIGS. 6 and 7.

Positioned on the end of each of the side arms 38 is a tubular holder 44which extends perpendicular to the side arm parallel to the transverserod 20. A stylus, or axis pin, or other small diameter element 45 isslidably positioned in the tubular holder 44. A set screw 46 threadsinto the interior of the holder to lock the stylus in its desiredposition. On the inner end of the stylus 42 is mounted another tubularholder 46 in which is firmly positioned a scribe or writing element 48.The scribe 48 may be forcefully removed and replaced by another elementor transducer. The entire stylus can be a writing element is desired.

On the .[.other.]. .Iadd.outer .Iaddend.end of the stylus 45 is slidablymounted a ring shaped marker 50 which is made of teflon, plastic orother suitable material which will grip the stylus 45 but yet may bemanually slid on the stylus.

CLUTCH AND TOOTH SEPARATOR

Referring to FIGS. 10-13, a T-shaped support member 60 is mountedbetween two halves of the transverse rod 36. A pair of clutch pieces 62and 64 are attached to the support 60 by means of a screw 65. As can beseen, each of the clutch pieces 62 and 64 includes strut .[.position.]..Iadd.portion .Iaddend.whose forward end is attached to the support 60and whose rearward end supports a curved portion adapted to fit over thelower teeth or gums of the patient. Each of the clutch strut portionsincludes a depending flange 62a and 64a. An adjusting screw 66 isthreadedly mounted in the flanges so that the spacing between the clutchpieces 62 and 64 is laterally adjustable by means of the screw 66.

Pivotally mounted on the transverse rod 36 is a tooth separator 70. Morespecifically, the separator 70 includes a base plate 71 having a pair ofarms straddling the clutch support member 60 and which fit over thetransverse rod 36 so that the base plate is swingable about the rod. Thebase plate 71 further includes a flat portion of which is mounted aseparator or contact element 72. The separator element has a pair ofside flanges with elongated mounting slots 74 which receive screws 76threaded into the separator base plate 71. This arrangement of coursepermits front to rear adjustment of the separator elements 72 withrespect to the base plate 71. The upper surface of the separator element72 is smoothly curved into an arch shape from side to side as seen inFIGS. 11 and 12. Also, as seen by FIG. 12, the element 72 slopesdownwardly in the forward direction. The patient's upper teeth or gumsengage the upper surface of the separator element 72. The height andshape of the arch may be selected to best fit the patient's mouth.Various separator elements may be employed since they are readilyseparable from the base plate 71.

As may be seen from FIG. 10, the separator may be swung out of operatingposition, or may be positioned in operating position as .[.shwon.]..Iadd.shown .Iaddend.in FIG. 11. In this latter position, the base plate71 is supported by an adjustable screw 78 which is threadedly mounted inthe .Iadd.strut .Iaddend.portion of the clutch element 64.

STRAIGHT EDGE TOOL

Referring to FIG. 14, there is shown a straight edge tool 80 to be usedwith the upper frame for marking the horizontal plane of reference forthe jaw movements measured. As can be seen, the tool has a generallyU-shaped formed by two L-shaped flat plates 81 and 82. The right plate81 as shown in FIG. 14 has a recess 83 in its transverse leg 81a whichreceives the transverse leg 82a of the left plate. The depth of therecess is equal to the thickness of the left plate so that the uppersurfaces of the two plates are in the same plane. The recess 83 in theright plate permits lateral adjustment of the plates so as to vary thedistance between the rearwardly extending parallel legs 81b and 82b ofthe plate. To lock the plates at the selected position, there isprovided an elongated slot 84 in each of the overlapping legs 81a and82a of the plates with said slots being aligned so that a bolt 85extends through the slots and a locking nut 86 is threaded onto the boltto clamp the plates to each other.

A pointer receiving element 88 is clamped to the tool by means .[.for.]..Iadd.of .Iaddend.another nut 89 and bolt 80 combination extendingthrough the slots 84 in the left and right plates. Thus, the element islaterally adjustable by moving the bolt 90 laterally. The element alsohas an elongated slot 91 formed therein which permits it to beadjustable from front to rear, or angularly. Formed in one edge of adepending lug at the forward end of the element 88 is a dimple 92 forreceiving the pointer 33 on the upper frame. As can be seen from FIG.15, the center 92a of the dimple is precisely aligned with the uppersurface of the plate of U-shaped tool 80 so that the dimple is in thesame plane with the upper surface.

OPERATION

As the first step for utilizing the apparatus of the invention, thelower frame 14 without the side arms 38 is attached to the patient'smandible. The clutch elements 62 and 64 shown in FIG. 10 are laterallyadjusted by means of the adjusting screw 66 to fit the patient's lowerjaw. The tooth separator 70 should be swung to the position shown inFIG. 10 where it is not in operating position. The lower side of theclutch elements 64 and 62 which extend into the patient's mouth is thenfilled with a denture compound or plastic. While the compound is stillpliable the clutch is inserted into the mouth over the lower teeth sothat the compound is pressed onto the buccal surfaces of the teeth.After the compound hardens the clutch may be removed from the teeth.Denture paste is then inserted into the compound and the clutch isreinserted over the lower teeth. After several minutes, the paste willhave hardened so that the clutch attached to the transverse rod 36 issecurely fixed to the teeth.

The upper frame .[.21.]. .Iadd.12 .Iaddend.is now positioned on thepatient. The set screws 21 and 22 are loosened so that the apparatus maybe positioned over the patient's head. The nasion positioner 28 isrotated to fit the particular shape of the nose. The patient holds thenasion positioner against the nose while the operator moves the sidearms 15 and 16 inwardly towards the patient's head and front to back,until the grid plates 24 are positioned just in front of the ears andthe side arms fit snuggly against the side of the head. The rear portionof the side arms rest next to the head on top of the ear. The set screws21 and 22 are not tightened in this position to hold the side arms infixed relation perpendicular to the transverse rod 20. The elastic strap26 attached to the ends of the side arms is positioned around the backof the head to help hold the upper frame in proper position.

The pointer 33 which is previously loosened on its mount is movedtransversely to engage the patient's nose a predetermined distance belowthe transverse rod 20, and the pointer is then locked in such position.

The adjustable side arms 38 of the lower frame 14 are now slid onto thelower transverse rod 36 and moved inwardly until the writing elements 48engage the grid on the recording plates 24. Note that the lateral orouter ends of the scribe holders 47 must be spaced sufficiently from thestylus supports 44 to allow for lateral jaw movements. Four to fivemillimeters should accommodate any such movement.

As a next step, the patient's hinge axis in centric relation positionshould be located. The tooth separator 70 is swung inwardly into thepatient's mouth so that the patient's upper front teeth or ridge willengage the upper surface of the curved separator element 72 as may beseen in FIG. 14. The patient's mandible is opened and closed while inthe terminal hinge position, that is, where the lower jaw is in its mostrearward position. It is important that the back teeth be slightlyseparated in that the muscles of the jaws tend to draw the lower jawinto its rearwardmost position, but the rear teeth could act as afulcrum and interfere with this action if the upper and lower teeth arenot separated. Thus it would be more difficult to keep the lower jaw inits hinge axis position.

As the patient's mandible is moved up and down in the terminal hingeposition, the side arms 38 of the lower face bow 14 should be adjustedvertically and from front to back until the writing elements, or scribes48 no longer arc, but simply rotate. The grid lines on the plates 24 arehelpful in this step as they act as references. This is the point wherethe hinge axis exits from the .[.hand.]. .Iadd.head .Iaddend.and is thestarting point for the recording measurements. Consequently, with theside arms 38 so positioned, the set screws for positioning the side armsare locked so that the scribes 48 are fixed in aligned relation with thepatient's hinge axis. This point is illustrated at 93 in FIG. 20.

To measure the protrusive movement, the patient's mandible is placed inthe terminal hinge position or centric relation position and the twoaxis styluses 45 are pushed inwardly so that the scribes 48 are tightlyagainst the grid plates 24. The styluses are then locked with the setscrews 46. The patient then protrudes the lower jaw while the twoscribes 48 trace a path P of the protrusive movement on the grids. Sincethe upper wall of the human temporomandibular joint usually slopesdownwardly, the patient's condyles will usually move downwardly as theymove forward. This is indicated in phantom lines in FIG. 15. Because ofmovement in this fashion, the path P traced on the grids slopes orcurves downwardly as shown in FIG. 20. The slope of this downward andforward curve may be read on a suitable reference line on the grid.

While the angle of protrusive movement may be measured with respect to ahorizontal line on the grid which is parallel to the side arms of theupper frame, it is preferable that the angle be measured with respect tothe true horizontal plane of reference formed by the terminal hinge axisposition and the point which is located on the side of the patient'snose by the pointer 33. This is preferred because this is the referenceplane used for mounting denture casts in an articulator.

The reference plane straight edge or tool 80 is used to physically markthe plane on the grid paper on the plates 24, as shown in FIGS. 18 and19. More specifically, after the protrusive and lateral jaw movementcurves P and L, FIG. 20, are marked on the grids, the upper frame 12 isremoved from the patient and the U-shaped reference plane tool 80 ispositioned to straddle the arms 15 and the recording plates 24 on theupper frame. The legs of the U-shaped tool are laterally adjusted sothat they just engage the outer sides of the recording plates 24. Thepointer 33 is positioned in the dimple 92 formed in the element 88attached to the reference plane tool, as shown in FIG. 15A. Note thatthe element 88 can be adjusted laterally and rearwardly to easilyreceive the pointer. With the forward end of the tool so positioned bythe pointer, one leg of the tool is aligned on the recording plate 24which it engages so that the hinge axis point 93 is in the referenceplane forming the upper surface of the tool. The tool is temporarilyclamped in this position by a suitable clamp 98 shown in FIG. 16. Theother leg of the tool is then similarly positioned on the otherrecording plate. By using the tool as a straight edge, a line 95 canthen easily be drawn on the grid paper on the recording plate throughthe hinge axis 93 to represent the reference plane, shown as 95a in FIG.17. Such a reference line 95 can be marked on both the grids. Thereference plane tool 80 is then removed so that the protrusive angle canbe readily measured with a protractor 96 or other similar tool.

It will be noted that the slope of the protrusive curve P changes. Thus,it can be measured at any number of points as desired or can beconstantly monitored. If comparisons are desired between recording.[.plaaes.]. .Iadd.plates .Iaddend.of various patients, a standardmeasurement point with respect to the hinge axis point 93 can beselected.

Referring to FIGS. 8 and 9, another measurement to make is the sideshift or lateral displacement of the condyles when the jaw is moved toone side as in chewing. First, the mandible is placed in centricrelation position. Second, the stylus is pushed inwardly until thewriting tip touches the recording plate. Third, the adjustable screw 46is tightened to lock the stylus 45 and the marker 50 is slid inwardly onthe stylus 45 until it is engaging the outer or lateral surface 44a ofthe holder 44, as seen in FIG. 8. Next, the adjustable screw 46 lockingthe stylus 45 with respect to the holder 44 is loosened on one side ofthe lower frame. The mandible is then moved directly laterally to theextent possible in the direction to move the side of the lower frame onwhich the screw 46 has been loosened toward the adjacent recordingplate. In other words, referring to FIG. 9, the arm 38 is moved, asindicated by the arrow, toward the recording plate 24. The stylus 45cannot move in that direction because its inner end 48 is in engagementwith the plate 24 on the fixed upper frame. Instead, the holder 44 onthe arm 38 slides inwardly on the stylus 45. The marker 50 remains fixedon the stylus 45 and thus the reference surface 44a is spaced from themarker 50. it is a .[.simple.]. .Iadd.small .Iaddend.matter to measurethe displacement 53 of the holder 44 which represents the direct orimmediate mandibular side shift in one direction. A similar procedure isfollowed to obtain the side shift in the other direction.

Also the so-called full mandibular side shift is obtained in this mannerbut the mandible is allowed to make a more complete side chewingmovement. During a full chewing movement, the mandible moves forwardlyas well as laterally. The border of this combined movement can berecorded by having the stylus 45 trace the path of the hinge axis motionon the vertical plates simultaneously with the side shift measurement.For this purpose, an elastic or small spring 98 shown schematically inFIG. 8a is employed to urge the stylus against the plate at all times sothat a tracing is obtained. The elastic 98 extends between the holder 44and the outer element 51 tightly mounted on the stylus 45. Referring toFIG. 20, the path L of this full chewing movement usually has a steeperslope than that of the protrusive movement P.

As the hinge axis moves during a side chewing movement producingdownward and forward slope on one side of the head as evidenced by thepath L, the stylus on the other side of the head representing movementof the other end of the hinge axis is moved upwardly and rearwardly asmall amount. This path which is shown on FIG. 20 as B and oftenreferred to as backlash, is caused because the tip of the scriberecording the path is spaced laterally from the condyles within thehead.

While the border path of the side chewing movement is being recorded onthe grid record plate 24, the complete side displacement is beingmeasured by the markers 50 being displaced relative to the referencesurfaces 44a on the holders 44. By returning the mandible back tocentric position, the displacement is easily measured. This displacementis shown at 55 in FIG. 9a as typically being considerably greater thanthe immediate side shift 53 in FIG. 9.

ELECTRONIC MEASURING MEANS

As mentioned above the movement of the styluses 48 may be monitoredelectronically as well as mechanically. Such an arrangement isschematically illustrated in FIG. 21 wherein the stylus is in the formof a current inducing probe 100 supported on an arm 101 of a lowerframe, and connected to a signal source 120. A recording plate 102attached to the upper frame has a grid 103 of insulated electrical wiresembedded in a thin sheet 104 rotatably supported on the surface of therecording plate by three clips 105, which grip the sheet 104 but permitlimited rotation in order to align the grid with the true horizontalreference plane. The sheet 104 is transparent on its outer surface sothat the wires are visible and can serve as alignment grid lines. Alsothe sheet is sufficiently self-supporting so it remains flat whensupported on its edges in the vertical orientation shown.

As the patient's jaw is moved into protrusive position, the probe 100 ismoved adjacent the surface of the sheet 104 inducing current in the gridof wires 103, as the probe crosses a wire. These current signals aresensed and recorded, on suitable readouts, indicating the movement onthe surface of the recording plate. In the arrangement shown, thesignals produced in crossing the vertical wires, that is, movinghorizontally, or in the X axis direction, are displayed on an X-movementreadout 106 and the signals resulting from a crossing of the horizontalwires, that is, moving vertically, or in the Y axis direction, aredisplayed on a Y-movement readout 107. The output may be shown oncounters or they may be combined and shown on an oscilloscope typedisplay, if desired. In either event the position of the probe along thesurface of the record plate is thereby monitored.

The details of the current inducing probe, the grid, and the readoutsare not disclosed herein in that such position identifying devices areprior art. For example, U.S. Pat. Nos. 3,461,454 and 3,647,963 eachdisclose systems that could be adapted to this purpose. Moreover, thereare a variety of digitizers known in the prior art which could beutilized in such an application.

In use, the arm 101 of the lower frame is adjusted until the hinge axisis located, and the arm is then fixed to the transverse rod 36 of thelower face bow. The hinge axis is located when arcuate movement of theprobe 100 stops, as indicated by the X and Y readouts 106 and 107, asthe mandible is opened and closed. Before protrusive movement iscommenced, suitable adjustments may be provided to make the protrusivemovement readings measurable with respect to the reference plane 95adefined by the hinge axis and the pointer 33. As one approach, areference plane tool (not shown) similar to the tool 80 but adapted tobe positioned over the upper face bow while the bow is on the patient isthen aligned with the probe 100 and the nose pointer 33, FIG. 18. Thegrid sheet 104 is then rotated so that its horizontal lines are parallelwith the planing tool. The plane tool is then removed, the readout setto zero; and protrusive movements commenced. The slope of the protrusivecurve can be determined from the readout information on the XY axes ofthe grid. It should be noted that this method of having the grid sheetrotatable to align the horizontal lines on the grid with the referenceplane 95a can also be used in the mechanical arrangement discussedabove.

For measuring the side displacement of the lower jaw, or in other words,the movement of the lower frame in the lateral or outward direction,other known plotting arrangements may be employed. For example, theprobe 100 is urged against the grid 103 by a spring 122 confined in aholder 108 which supports the probe 100 and is attached to the side arm101. A transducer unit 109 mounted on the holder 108 adjacent the probe100 is provided to measure the lateral movement of the holder withrespect to the probe. The probe is provided with suitable markings 100awhich are monitored or counted by the transducer unit 109. The output ofthe transducer is transmitted to a suitable Z axis readout 110 forindicating side shift. The transducer 109 is well known in the art, onesuch arrangement comprising a light source, a small metrologicalgrating, and a photosensitive cell. The output of the photosensitivecell is a series of pulses; each pulse indicates that the holder hasmoved a predetermined incremental distance. Further details regardingsuch a sensing arrangement may be found in U.S. Pat. No. 3,434,218. Itshould be understood that a variety of methods are known for monitoringand measuring such movement electronically. This horizontal or lateralmotion, monitored on the so-called Z axis, can be synchronized with thesignal from the XY positions so as to give a changing positional readingof the probe tip in relation to the XYZ axis of its starting position.In other words, at any given point in time in a specific jaw movement,the stylus tip position can be determined with respect to the horizontalreference .[.plans.]. .Iadd.planes .Iaddend.by the X, Y, Z coordinates.

USE OF JAW MOVEMENT INFORMATION a. Jaw Movement Simulators

With the apparatus and methods described above, jaw movements arereadily measured. Such information is useful for properly adjustingdental articulators which are utilized to simulate jaw movements. Thatis, the side shift, immediate and full, and the slope of the upper wallof the guide boxes used for controlling articulator movement can be set.For example, referring to FIGS. 22 and 23, there is shown a dentalarticulator or jaw movement simulator including a lower frame orassembly A and an upper frame or assembly B which respectively representthe lower and upper jaws of a human for simulating jaw movement. In theposition illustrated, the upper assembly B can be pivoted on the lowerassembly A which is reverse to the human mandible or lower jaw whichslides with respect to the maxilla or upper jaw, however the relativemotion between the two frames is the same.

The lower assembly A includes a generally T-shaped base member 210having a forward arm 211 and an incisal pin rest pad 212 mountedthereon. Mounted on top of the rear of the base member 210 is a verticalframe member 220 supporting a pair of spaced spherical styluses 225which represent the simulated horizontal or hinge axis of the condylesof a human. A screw 231 projects upward through an opening in the arm211 for attaching a dental mounting plate schematically illustrated at232.

The upper assembly B of the articulator includes a T-shaped upper framemember 240 having lateral slotways 245 in its transverse arm 242.Attached to the forward end of the forward arm 241 is an incisal restpin 260 which has its lower end supported on the upper surface of therest pad 212 on the lower assembly. A horizontal flag 264 used toindicate the horizontal plane of reference is attached to the forwardend of the arm 241 immediately to the rear of the incidal pin 260. Theundersurface of .[.theis.]. .Iadd.this .Iaddend.flag forms a horizontalplane with the hinge axis through the styluses 225 when the guidehousings are at centric relation position. The forward arm 241 isadapted to receive a mounting plate for a maxillary dental castschematically illustrated at 252 in FIG. 22.

Attached to the outer arms 242 of the upper frame assembly are a pair ofguide assemblies 270 which cooperate with the styluses 225 of the lowerframe. Attached beneath the arm 242 for each guide assembly is amounting plate 272 having a trunion portion 272a (FIG. 24) to which isattached a mating trunion member 273 by suitable fastening elements 273aseen in FIG. 23. Each guide assembly 270 includes a pair of irregularfive wall guide boxes 271 whose walls are formed by a primary guidehousing 278 and a secondary member or housing 280. Referring to FIG. 26as well as to FIGS. 22-25, the primary guide housing 278 has a generallyflat upper wall 278a, a generally flat rear wall 278b, and a generallyflat outer wall 278c. The primary guide housing 278 also includes amounting end 278d having a retained cup-end shaft or pin 282 which isgripped by the trunions 272a and 273. The primary guide housing 278 isjoined to the pin 282 to act as one piece, and hence the entire guidehousing can be rotated horizontally as desired with the pin 282 andclamped in this position by means of the fastener 273a. An angular scale279 is formed on the trunion 273 as shown in FIG. 24 to indicate theangular orientation of the guide housing 278 to the horizontal plane.Thus the general slope of the protrusive path 94 shown in FIG. 20 isused to set the angle of the guide housing 278, the information beingmeasured by the protractor 96 or shown on the electronic readout 106 and107 of FIG. 21.

The secondary guide housing 280 is an irregularly shaped elementpreferably formed as an integral piece which fits onto the primaryhousing 278. The secondary housing 280 includes a horizontally flatupper support arm 280a, (when viewed in the orientation of FIGS. 22 and25) a vertical wall 280b, a flat vertically orientated but horizontallyextending wall 280c attached to the vertical wall 280b, and a generallyflat, curved, finger-like front guide wall 280d extending outwardly fromthe walls 280b and 280c. The flat support arm 280a is mounted on theprimary guide housing with a pivot pin 286 by means of a set screw orother suitable means not shown. Referring to FIG. 27, the opening 287through which the pin 286 extends is elongated laterally so that the pin286 carrying the inner guide wall 280c may be moved inwardly a smallamount, such as about 2 millimeters. An adjustment of this type for bothright and left guides thus may provide a total horizontal side shift of4 millimeters. A set screw 288 extending through the rear wall 278b ofthe primary guide housing 278 engages either one side or the other ofthe pivot pin 286 to laterally fix the pin 286 and the secondary guidehousing 280 and also to prevent rotation once the desired angularsetting of the inner wall 280c has been made. The vertical support wall280b of the secondary housing 280 extends adjacent the forward edge ofthe housing 278 and the internal surface of the horizontally extendingvertically oriented wall 280c forms the inner or medial surface for theguide box 71.

Thus, the side shift information obtained as discussed above inconnection with FIGS. 7-9 is used to set the lateral position of the pin286 in the slot 287. Structure to provide fine degrees of adjustment maybe utilized if desired. The angle of the member 280, and thus the angleof the medial wall 280c of the guide box is set by using side shiftmeasurement (Z axis) and forward movement information (X axis) during achewing operation. Referring to FIG. 27, the X axis information ismeasured in the forward direction on the O angle line, and the Z axisinformation is measured perpendicular to the O angle line. In the caseof the electronic measuring means, the X and Z readings are convenientlyavailable at any point, and can be scaled off on the guide housing atany point in setting the member 280. In the case of the mechanicalarrangement, the maximum or full side shift, as determined above inreference to FIGS. 7-9, has been found to be near where the paths P andL of FIG. 20 stop moving downwardly or in the Y direction. The fullchewing side shift is typically obtained at about the ten millimetermark on the X axis. Thus a mark 290 may be conveniently formed on thezero angle line on the upper side of the guide housing 278 tenmillimeters from the hinge axis in centric position through the centerof the pin 286, as shown in FIG. 27, and the full shift measurementutilized at that point to position the member 280. A scale for full sideshift may be marked on the member 280 if desired.

In some articulators available, the slope of the upper surface 278a ofthe guide box adjacent the medial wall 280c can be separately adjusted.Information for this is obtained from the slope of the curve L in FIG.20 or from the electronic readout on the XY axes while in side chewingposition. Also some articulators can make adjustments for backlash B andthis information is available from the grid plate in FIG. 20 or from theelectronic readout.

b. Preformed Analogue Guide Blocks

The information obtained may also be utilized for preparing or selectingopenings in analogue guide blocks which when used with an articulator inplace of the guide boxes 271 of the simulator in FIGS. 22-27, moreprecisely duplicate or simulate the joint movements. One such set ofblocks 111 having openings 113 is shown in FIG. 28, by way of example.

For convenience of comparison, the guide blocks 111 are shown orientedsimilar to the guide boxes 271 of the simulator shown in FIG. 26. Whilethe guide boxes are straight line and have generally planar walls, thewalls of the guide blocks are usually curvilinear and thus moreaccurate. The points 114 in FIG. 28 mark the location of the styluses225 of FIG. 26 when positioned in the five-sided irregularly shapedguide block pathways or openings 113 in centric relation. The upper wall115 of the guide blocks corresponds to the wall 278a of the guide boxes271, while the lateral wall 116 and medial wall 117 correspond to theguide box walls 278c and 280c respectively.

As mentioned above in connection with the earlier Lee patent, theprocedure of machining a special set of analogue blocks for each patientis somewhat expensive. Such blocks have now been made on a relativelylarge number of patients and the characteristics of these blocks havebeen analyzed. This analysis discloses that most of the joint movementsmay be classified into a relatively small number of categories. Forexample, by classifying the pathways of the analogue blocks into justthree variations of immediate side shift and three variations of theslope of the protrusive curve, nine relatively broad categories arecreated. FIG. 29 is a table introducing two other variables for a totalof 36 categories. The first column indicates immediate side shift ofzero, one millimeter and two millimeters. The second column indicatesthe slope of the protrusive curve at a selected location in 15°increments of 30°, 45° and 60°. Column 3 lists the slope of the lateralor border path as 45° or 60°. Column 4 specifies the full side shift in5 or 7 millimeters at 10 millimeters forward from centric, whichdetermines the angle of the medial wall.

By selecting these broad categories, analogue blocks having suchcharacteristics can be prepared in large quantities. A main advantage ofthis arrangement being that if only certain standardized sizes areutilized, the blocks can be made by inexpensive manufacturing techniquessuch as molding. Thus, when the jaw movement parameters of a patient aremeasured it is a simple matter to select a set of blocks which mostclosely fit these measured parameters. The cost of the blocks are suchthat possibly individual dentists can afford to maintain a supply. Thusthe desired set of blocks can be simply selected and mounted in anarticulator to quickly enable the patient's jaw movements to besimulated.

Naturally for those patient's having unusual jaw movements such thatthey do not fall into the standardized categories, the more precisetechnique of making a custom set of analogue blocks may be employed ifdesired. Also, it should be understood that the number of standardizedcategories can be increased to improve precision. For example, furtherbreakdowns in any of the variables in the chart of FIG. 29 can beemployed. Introducing additional variables or further refinements of theincrements would eventually .[.made.]. .Iadd.make .Iaddend.the selection.Iadd.process .Iaddend.somewhat difficult for an individual. Thus, theinformation could be stored in a computer and the computer programmed toreceive the patient's jaw measurements and .[.made.]. .Iadd.make.Iaddend.the proper selection of analogue blocks amongst thestandardized categories. With the electronic monitoring means formeasuring jaw movements, the number of classifications is almostinfinite, but the number of standard sizes would have to be kept at arealistic level to maintain the practicality of the system. If thecomputer could not match a specific patient's jaw measurements to any ofthe stock selections it would indicate that this individual's movementswere significantly different from all of the others. In this case thispatient should be recorded with the Lee method in the above-identifiedpatent and other related Lee patents.

What is claimed is:
 1. Dental apparatus for analyzing or recording jawmovements comprising:an upper frame having two thin flat rigid recordingplates, mounted to be positioned one on either side of a patient's headperpendicular to the horizontal axis of the patient's temporomandibularjoints, said plates having a grid formed on their outer surface; a lowerframe affixed to the patient's mandible, said mandibular frame having apair of side arms one on either side extending alongside but spaced fromthe patient's face, and means mounted on each of said side armsextending inwardly to engage said grids on the upper recording plates tomonitor or record mandibular movements on said grid; and means removablymounted on said upper frame for providing on said grid a reference linein a plane through said axis and a third point on the upper framealigned with a point on the patient's face or nose, whereby measurementsof said movements may be made in relation to said reference line.
 2. Theapparatus of claim 1 wherein said upper frame includes a transverse rodto be supported on a patient and side arms mounted perpendicular to thetransverse rod in a manner such that they cannot be moved out ofperpendicular relation.
 3. The apparatus of claim 1 including separatormeans mounted on said mandibular frame for extending into the patient'smouth to separate the mandible and maxilla during said mandibularmovements.
 4. The apparatus of claim 3 wherein said separator means ismovably mounted on said mandibular frame in a manner such that it can bemoved into the patient's mouth when jaw separation is desired and movedout of the mouth when desired, while the mandibular frame remainsaffixed to the mandible.
 5. The apparatus of claim 4 wherein saidmandibular frame includes a transverse rod on which said mandibular sidearms are mounted, and said separator means is pivotally mounted on saidrod.
 6. The apparatus of claim 3 including clutch means mounted on saidmandibular frame for securing the mandibular frame to the patient'smandible, and wherein said separator means is supported on said clutchmeans.
 7. The apparatus of claim 1 wherein said means engaging saidgrids comprises a pin which is movably mounted on each of saidmandibular side arms to be movable toward and away from the side arm,and a marker movably mounted on each of the pins movable by movement ofthe side arms relative to said pins as a measure of the lateral movementof a patient's mandible.
 8. The apparatus of claim 1 wherein the meansengaging said grids comprises a stylus for marking a path on said gridduring said mandibular movement. .[.9. In dental apparatus for analyzingand recording jaw movements, including a mandibular frame comprising:atransverse rod; clutch means for affixing the transverse rod to thepatient's mandible; a pair of side arms affixed to the transverse rod toextend rearwardly along the patient's face; and an element mounted oneach of said arms and extending inwardly to engage a point aligned withthe terminal hinge axis position of the patient's mandible, saidelements being movably mounted on said arms, a marker on each of saidelements for indicating movement of the arms toward and away from saidhinge axis points as a measure of the side movement of the patient'smandible..].
 10. .[.The apparatus of claim 9.]. .Iadd.In a dentalapparatus for analyzing and recording jaw movements, including amandibular frame comprising:a transverse rod; clutch means for affixingthe transverse rod to the patient's mandible; a pair of side armsaffixed to the transverse rod to extend rearwardly along the patient'sface; and an element mounted on each of said arms and tending inwardlyto engage a point aligned with the terminal hinge axis position of thepatient's mandible, said elements being movably mounted on said arms, amarker on each of said elements for indicating movement of the armstoward and away from said hinge axis points as a measure of the sidemovement of the patient's mandible, .Iaddend.wherein said markers gripthe elements but are also slidable when adequate force is applied. 11..[.The apparatus of claim 10.]. .Iadd.In dental apparatus for analyzingand recording jaw movements, including a mandibular frame comprising:atransverse rod; clutch means for affixing the transverse rod to thepatient's mandible; a pair of side arms affixed to the transverse rod toextend rearwardly along the patient's face; and an element mounted oneach of said arms and tending inwardly to engage a point aligned withthe terminal hinge axis position of the patient's mandible, saidelements being movably mounted on said arms, a marker on each of saidelements for indicating movement of the arms toward and away from saidhinge axis points as a measure of the side movement of the patient'smandible, .Iaddend.wherein said elements are axis pins slidably mountedon said arms and said markers comprise small rings made of a materialsuch as plastic which will grip the elements but yet will slide, whenadequate force is applied. .[.12. The apparatus of claim 9 including aholder mounted on each of said side arms, the axis of each holderextending perpendicular to the side arms said elements being slidablymounted on the holders, and means mounted on each of said holders forselectively gripping said elements..]. .[.13. The apparatus of claim 12wherein said element includes a writing element on its innermost end forwriting on a recording surface supported on a maxillary frame..]. 14.Apparatus for recording jaw movements comprising:an upper frame havingtwo plate-like members for positioning one on either side of thepatient's head overlying the patient's temporomandibular joints; a lowerframe for affixing to the patient's mandible including side armspositioned outwardly from said members; a probe supported on each sidearm extending towards said members with the probe tips positionedadjacent said members; and means connected to said probes and saidmembers for electronically monitoring movement of said probes relativeto said members including digital readouts to provide numericalinformation regarding the patient's mandibular movement useful forsetting or preparing a dental articulator to simulate a patient's.Iadd.jaw .Iaddend.movement.
 15. The apparatus of claim 14 wherein saidmembers include means for sensing movement of the probe.
 16. Theapparatus of claim 14 including means for biasing said probes againstsaid members, and said monitoring means include means for sensinglateral movement of said lower frame relative to said probe. .[.17. Amethod of recording the angle or path of mandibular axis motioncomprising the steps of:vertically supporting a pair of record plates,one on each side of a patient's face overlying the area of hinge axismotion of the patient's mandible; affixing a mandibular frame to thepatient's mandible, said frame having styluses affixed to the side armsof the frame and engaging said record plates; moving the patient'smandible while maintaining the styluses in contact with the plates toobtain a path of such movement on the record plates; and providing onsaid plates a reference line which is a plane through said hinge axisand a reference point on the patient's face or nose, whereby thecharacteristics of said path with respect to said reference line may bedirectly measured and used for preparing a dental articulator tosimulate the patient's jaw movements..]. .[.18. The method of claim 17wherein said record plate includes a thin sheet removably mounted on theexterior of the plate, and said stylus is a writing implement which willwrite on said sheet..].
 19. A method of measuring mandibular sidemovements comprising:affixing a frame to a patient's mandible; affixinga frame to the patient's maxilla; affixing to one of said frames a rigidsurface overlying the patient's temporomandibular joints; affixing tothe other of said frames a pin generally perpendicular to and inengagement with said surface, one of said surface and said pin beingslidably mounted to its frame; shifting the mandible sideways in thedirection to cause displacement between said one slidably mountedelement and its supporting frame; and measuring the displacement toobtain a measure of the sideways shifting of the mandible.
 20. Themethod of claim 19 wherein said displacement is measured electronicallyto provide a digital readout.
 21. A method of measuring mandibular sidemovements comprising:affixing to a patient's mandible frame having aside arm extending along the side of a patient's face; slidably mountinga horizontal pin on said arm, with the pin extending perpendicular tothe arm towards the patient's face; positioning the pin over .[.tnhe.]..Iadd.the .Iaddend.patient's temporomandibular joint in engagement witha fixed rigid surface overlying said joint; shifting the mandiblesideways in the direction to cause the side arm to be displaced on saidpin; and measuring the displacement of said .Iadd.side .Iaddend.arm withrelation to said pin.
 22. The method of claim 21 including axiallylocking the pin while it is in contact with said surface, positioning amarker on said pin in engagement with a reference surface on said frame,unlocking the pin and then moving the mandible sideways so that the sidearm is moved towards said fixed rigid surface and the displacement ofthe side arm relative to the pin is conveniently represented by thedistance between the marker and said reference surface on the frame. 23.The method of claim 21 wherein in said pin positioning step the pin isaxially aligned with the hinge axis of said joint with the mandible incentric position. . A method of recording the protrusive angle or curveof mandibular axis motion comprising the steps of:vertically supportinga record plate on the side of a patient's face overlying the hinge axisof the patient; supporting a stylus with its tip adjacent said recordplate; affixing a mandibular frame to the patient's mandible with one ofsaid plate and said stylus affixed to said frame and the other of saidplate and stylus being fixed with respect to the patient's maxilla; andelectronically monitoring the relative movement of said stylus and saidplate while moving the patient's mandible to thereby produce on digitalreadouts information of the movement useful for preparing a dentalarticulator to simulate a patient's jaw movement or for other dentaldiagnostic purposes.
 25. The method of claim 24 including the step ofestablishing a plane of reference through said hinge axis in centricposition and a point on the patient's nose so that the curve ofmandibular movement may be measured with respect to said referenceplane.
 26. The method of claim 25 including the step of positioning aflat reference plane tool on a nose pointer mounted on a frame mountedon the patient's maxilla and aligning the tool with said hinge axis aslocated by said stylus.
 27. Dental apparatus comprising:a maxillaryframe having a transverse rod to be supported on a patient's nose, apair of side arms attached to the tranverse rod to be supported on thepatient's ears, a pair of recording plates attached to the side arms tooverlie the patient's .[.temporomandiublar.]. .Iadd.temporomandibular.Iaddend.joints, and a pointer mounted on said transverse rod to engagethe patient's nose; and a reference plane tool to fit over the maxillaryframe having a pair of side legs to engage the recording plates, and anelement attached to the tool with a dimple therein for receiving saidnose pointer.[., said dimple being in the same plane as the uppersurfaces of said tool legs..]..Iadd.. .Iaddend.
 28. A tool for use witha maxillary recording frame comprising:a pair of L-shaped members havingflat upper surfaces; one of said members having a recess formed in oneleg for receiving a leg of the other member so that with the legsoverlapping the members together form a U-shaped, the depth of saidrecess being equal to the thickness of the leg received therein so thatthe upper surfaces of the two members are in a single plane, the widthof the U-shaped space between the members being adjustable by means ofthe recess and leg therein; and a point receiving element attached tosaid tool and extending outwardly from the tool, the point receivingelement having a dimple in an edge surface for receiving a nose pointerof a maxillary recording frame. .[.29. A method of simulating jawmovements comprising the steps of: measuring specified parameters of apatient's lower jaw movements; selecting from a preformed supply ofanalogue guide blocks having openings formed therein of standardizedsizes, classified on the basis of said specified parameters, the set ofblocks best fitting said patient's jaw movement parameters the openingin each of said blocks being adapted to receive a spherical stylus on adental articulator, said opening having an upper wall and wallsextending around the opening including an outer or lateral side wall, aninner or medial wall, a rear wall adjacent a centric position point, anda forward wall; and mounting the selected analogue blocks in a dentalarticulator to receive the articulator styluses and simulate thepatient's jaw movements..]. .[.30. The method of claim 29 wherein one ofsaid specified parameters is the jaw side shift from centric positionpermitted by the side walls of said opening..]. .[.31. The method ofclaim 30 wherein said side shift is the immediate or direct initiallateral jaw movement..]. .[.32. The method of claim 31 wherein anotherone of said specified parameters is the slope of a protrusive jawmovement at a specified location..]. .[.33. The method of claim 32wherein another of said parameters is the full side shift permitted at aspecified location forward from the centric point..]. .[.34. The methodof claim 29 wherein said supply of blocks is made by moldingtechniques..]. .Iadd.
 35. A method of simulating jaw movement comprisingthe steps of: positioning a rigid surface overlying a patient'stemporomandibular joint; affixing to a patient's mandible a frame havinga side arm; slidably mounting an element on said arm and engaging saidrigid surface; shifting the mandible sideways to cause relativedisplacement between said element and said arm; measuring saiddisplacement; and using the measurement of said displacement to preparea dental articulator to simulate the patient's mandibular movements..Iaddend..Iadd.
 36. The method of claim 35 wherein said using stepincludes selecting from a preformed supply of dental articulator stylusguide blocks, the set of blocks best fitting said patient's mandibularside shift, said guide blocks having openings formed therein ofstandardized sizes, classified on the basis of side shift, the openingin each of said blocks being adapted to receive a spherical stylus on adental articulator to guide the movement of the articulator..Iaddend..Iadd.
 37. A method of simulating jaw movement comprising thesteps of: affixing to a patient's mandible a frame having a side armwith an element connected therewith which is movable with respect to thearm; shifting the mandible sideways to cause said element to moverelative to said arm to provide an indication of the displacement of themandible; and measuring said displacement. .Iaddend. .Iadd.38. A methodfor recording the path of mandibular axis motion and utilizing such pathto prepare a dental articulator, comprising the steps of:supporting arecord plate overlying the area of hinge axis motion of the patient'smandible; affixing a mandibular frame to the patient's mandible, saidframe having a stylus affixed to the side arm of said frame and engagingsaid record plate; moving the patient's mandible while maintaining saidstylus in contact with said plate to obtain a path of such movement onsaid plate; providing a reference line which is in a plane through saidhinge axis; and using said path to prepare a dental articulator tosimulate the patient's jaw movement, wherein said using step includesselecting from a preformed supply of articulator stylus guide blockshaving openings formed therein of standardized sizes classified on thebasis of types of said paths, the set of blocks best fitting thepatient's jaw movement characteristics, the opening in each of saidblocks being adapted to receive a spherical stylus on a dentalarticulator and having a plurality of guide walls defining the openingfor guiding movement of the spherical stylus. .Iaddend. .Iadd.39. Areference plane tool for use with a maxillary recording framecomprising:a pair of L-shaped members with one leg of each in contactwith each other to form the base of a U-shaped element, a portion ofeach of the other legs of said L-shaped members being in the same plane;means for fixing said members relative to each other; means forming adimple laterally adjustable on said base; and means for fixing saiddimple on said base. .Iaddend. .Iadd.40. The reference plane tool ofclaim 39 further comprising clamps on said recording frame forsupporting said other legs. .Iaddend. .Iadd.41. A reference plane toolfor use with a maxillary recording frame, comprising: a structure havingtwo legs, a portion of each of said legs being in a single plane; meansfor adjusting the distance which separates said legs; and means forengaging a maxillary recording frame whereby said legs are positionedrelative to said recording frame to provide it with a reference linewhich is in a plane through the patient's hinge axis. .Iaddend..Iadd.42. The reference plane tool of claim 41 wherein each said portionof said legs forms a guide for providing a record plate attached to saidrecording frame with a reference line, and wherein said means forengaging defines a point which is in the same plane as saidguides..Iaddend. .Iadd.43. The reference plane tool of claim 41 furthercomprising means for supporting said legs in their position relative tosaid recording frame..Iaddend. .Iadd.44. A reference plane tool for usein forming a reference line through the hinge axis of a patient in orderto set a dental articulator, comprising: a structure having two legs;means on said structure for locating said structure with respect to afixed reference location wherein said legs are each respectivelypositioned adjacent the opposite sides of the patient's head and areeach positioned relative to said hinge axis to provide a reference linewhich is in a plane through said hinge axis and another point..Iaddend..Iadd.45. The reference plane tool of claim 44 further comprising meansfor supporting said legs in their position relative to said hingeaxis..Iaddend. .Iadd.46. A reference plane tool for use in forming onrecording plates on opposite sides of a patient's head a reference linethrough the hinge axis of a patient in order to set a dentalarticulator, comprising:a structure having two members; means on saidstructure for locating said structure with respect to a fixed referencelocation wherein said members are each respectively positioned adjacentthe recording plates and are each positioned to provide a reference linewhich is in a plane through said hinge axis and another point; and meansfor supporting said members adjacent the recording plates..Iaddend..Iadd.47. Dental apparatus, comprising: a maxillary frame having atransverse rod, a pair of recording plates attached to said side arms tooverlie the patient's temporormandibular joints: and a reference planetool having a pair of side legs and means for engaging said maxillaryframe whereby said legs are positioned relative to said recordingplates, and provide them each with a reference line which is in a planethrough the patient's hinge axis. .Iaddend. .Iadd.48. The apparatus ofclaim 47 wherein said means for engaging includes means for locatingsaid reference plane tool relative to said maxillary frame such thatsaid reference plane passes through a point on the side of the patient'snose..Iaddend. .Iadd.49. The apparatus of claim 47 wherein said legs arepositioned relative to said surfaces to provide them each with areference line, both of said lines lying in a single plane through thepatient's hinge axis..Iaddend. .Iadd.50. The apparatus of claim 47further comprising means for supporting said legs in their positionrelative to said side legs..Iaddend. .Iadd.51. A method of recording apath of mandibular motion and utilizing such path to prepare a dentalarticulator, comprising the steps of:supporting a record plate overlyingthe hinge axis of the patient's mandible; affixing a frame to thepatient's mandible, said frame having a stylus affixed to the side armof said frame and engaging said record plate; moving the patient'smandible while maintaining said stylus in contact with said plate toobtain a path of such movement on said plate; positioning a referenceplane tool adjacent said record plate to provide a reference linethrough said hinge axis and a reference point on the patient's face ornose; and using information gained from said path with respect to saidreference line to set a dental articulator. .Iaddend. .Iadd.52. Themethod of claim 51 including:providing a record plate on each side ofthe patient's face overlying said hinge axis; and utilizing said tool toform a reference line on each of said plates, with both of said linesbeing in a single plane defined by said hinge axis and said referencepoint..Iaddend. .Iadd.53. The method of claims 51 or 52 includingsupporting said record plates on a frame which is supported on thepatient's ears and nose, and positioning said tool to be aligned withthe hinge axis on a record plate and engaging a reference point on saidframe..Iaddend. .Iadd.54. The method of claim 52 wherein said recordplates are supported on a frame supported on the patient's ear and noseand said tool is a generally U-shaped structure, and including the stepsof supporting each leg of the tool on a respective one of said recordplates with a straight edge on each of said legs aligned with said hingeaxis on said plates, while positioning a central portion of the tool incontact with a reference point on said frame to form reference lines onsaid plates in a single reference plane. .Iaddend.